Field of the Invention
The invention relates to a method of administering supplementary services in a communications network and to a service control unit or service switching unit configured for the method. The supplementary services are capable of being used in accordance with an intelligent network structure.
Communications networks are configured as fixed networks or mobile communications systems, such as the known GSM mobile radio network (Global System for Mobile Communications) and have interconnected switching centers. In mobile radio networks, base stations are respectively connected to the switching centers and can be used for connecting communication terminals via an air interface. The communication terminals permit network access for a subscriber of the mobile communications system. The switching centers also create the gateway to further networks, for example data transmission networks or a fixed network.
It is also known from the GSM mobile radio network to use memory units in which subscriber-specific data about the services of the network are respectively stored. One of the memory units realizes the so-called home location register, which is generally at a permanently defined location and in which the data on which the registration of the subscriber is based are stored. A memory unit is provided for the location of the mobile subscriber at any given time, as a so-called visitor location register. Depending on the location of the mobile subscriber, the memory unit for the visitor location register in which the data specific for the subscriber are located also changes.
The supplementary services with which the invention is concerned are to be realized in accordance with an intelligent network topology by independent service control units. The service control units and the profiles stored therein of the supplementary services, including the information necessary for their realization, are consequently modifiable independently of the mobile communications network. It is known from Published, Non-Prosecuted German Patent Application P 44 42 305 A that the services which can be used in an intelligent network are initiated in a service switching unit in order to leave the customary call processing and consequently activate access to supplementary services. Such service switching units are generally realized in the switching centers.
It is generally known to provide a service indicator as a subscriber-individual subscriber datum in the respective subscriber database and, by evaluating the service indicator during call handling in the case of an incoming or outgoing call, to initiate branching to a service control unit specified in a subscriber database of the intelligent network.
Also known, from xe2x80x9cThe CAMEL Feature, Proposed Revisions To The Stage 1 Descriptionxe2x80x9d, from ETSI/STC/SMG1. 14.03.95, GSM 02.78, Version 0.4.0, pages 1-14, is a so-called customized application for mobile network enhanced logic (CAMEL) platform, with which the support of supplementary operator-specific services for subscribers is to be made possible. Consequently, an operator-specific supplementary service can be used even beyond the network and service limits of a communications network. This is possible if the service switching unit initiating the supplementary service can process the required protocol (CAPxe2x80x94CAMEL application part) for the service requested and if signaling messages from and to the home location register and the service control unit of the supplementary service can be exchanged beyond the network limits.
A prerequisite for a subscriber to use the supplementary service is that the service switching unit with which the subscriber is connected can support the supplementary service with the corresponding protocol. The full-coverage provision of the supplementary service consequently requires conversion of all the service switching units and a signaling message exchange for the selection of one of the corresponding protocols.
It is accordingly an object of the invention to provide a method of administering supplementary services in a communications network which overcome the above-mentioned disadvantages of the prior art methods and devices of this general type, in which supplementary services are accessible to a greater number of users and entails only a low retrofitting effort.
With the foregoing and other objects in view there is provided, in accordance with the invention, an improved method of administering supplementary services in a communications network having connection equipment, a gateway for connecting to at least one further network, networked switching centers connectable via the connection equipment to communication terminals for permitting subscriber access and via the gateway to the at least one further network, service switching units connected to the connection equipment and the gateway, and at least one service control unit controlling a supplementary service of the supplementary services, the improvement which comprises:
sending an initiating message from a first service switching unit of the service switching units serving a subscriber to the at least one service control unit;
performing a comparison of a first protocol supported by the first service switching unit with a second protocol necessary for the supplementary service; and
determining a second service switching unit of the service switching units that can support the second protocol necessary for the supplementary service, and rerouting to the second service switching unit in dependence on a result of the comparison.
The method according to the invention of administering supplementary services provides that the initiating message is sent from the first service switching unit, serving a subscriber, to the service control unit assigned to the supplementary service. In the service control unit there then takes place a comparison of a protocol supported by the first service switching unit with a protocol necessary for the supplementary service. Depending on the result of the comparison, i.e. if the protocol supported by the first service switching unit is not adequate for supporting the supplementary service, a second service switching unit, which supports the protocol necessary for the supplementary service is determined. A rerouting to the second service switching unit is then initiated.
New supplementary services can be initially introduced using the method according to the invention in only one service switching unit and nevertheless be offered in the entire network and in visited networks that support a CAMEL phase 1. This considerably reduces the effort for introducing supplementary services. The procedure also makes it much easier to carry out a test of a new supplementary service.
The method according to the invention can be used if the calling subscriber or the called subscriber uses a supplementary service that is supported by a service control unit. It can similarly be used if the first service switching unit has been selected by call forwarding. Managing the entries on the protocols available in the individual service switching units just in one or more service control units makes it possible for the entries to be easily maintained and amended. The service switching units do not have to be adapted to the same extent.
It is consequently also possible to use non-standardized protocols, for example ETSI Core INAP and network-specific variants for mobile radio networks (for example TELECOM INAP), or various CAP (CAMEL application part) versions, which are supported both in the network of the subscriber registered for the supplementary service and in a visited network if only a single service switching unit or a few service switching units support the specific protocol. For roaming subscribers, the necessary prerequisite is that CAP phase 1 is supported by the respective service switching unit.
According to an advantageous development of the invention, particulars on the protocol required for the supplementary service are stored in the service control unit, on the basis of which the second service switching unit is selected. This reduces the signaling effort and makes it easy for the entries on the protocols to be amended. Particulars on a plurality of service switching units, designating the protocols available there and further attributes, are advantageously also stored in the service control unit. This also reduces the signaling effort between the service control unit and the service switching units.
According to a further advantageous development of the invention, a service switching unit which is in a specific relationship with the first service switching unit is selected as the second service switching unit. If there is a possibility of selection between a plurality of service switching units, an expedient selection can be made with knowledge of the first service switching unit.
A service key for the supplementary service and an address of the first service switching unit are advantageously used for selecting the second service switching unit, with the result that a second service switching unit close to the first service switching unit is determined with the aid of a table. As an alternative to distance-related criteria, cost and effort considerations or the specific agreements between the operators of various communications networks may be used.
If particulars on a communications-network-specific address of the second service switching unit (for example an E.164 address in the GSM mobile radio system) are also included, it is possible to dispense with a further conversion of a designation of the service to an address of the service control unit.
The connection between the first service switching unit and the service control unit is advantageously cleared after the comparison, in order to reduce the switching effort in the network. The data received by the first service switching unit during the dialog are buffer-stored in the service control unit and provided with correlation information, in order to have the buffer-stored data available again when setting up the communication between the second service switching unit and the service control unit.
A further development of the invention provides that a routing address is created for the rerouting, the address includes an address of the second service switching unit, an indicator for the rerouting of the supplementary service, an address of the service control unit, and a protocol indicator. Consequently, the immediate setting up of a connection between the second service switching unit and the service control unit is simplified.
According to a further advantageous development of the invention, particulars on the supplementary service requested by the subscriber, which are designated by correlation information, are stored in the service control unit. The correlation information is transferred as part of the rerouting address, with the result that, when a connection is set up between the second service switching unit and the service control unit, an assignment of the connection with the supplementary service and the particulars stored with respect to it is possible. A timing circuit, which for a predeterminable time period expects the setting up of a connection with the second service switching unit, is advantageously included in the service control unit. If this time period is exceeded, the buffer-stored particulars are erased. These measures serve the purpose of not unnecessarily tying up the resources in the event of a malfunction.
A decentralized introduction of extended possibilities for supplementary services is alternatively permitted by using a service key and an address of a service control unit intended for the supplementary service in a service switching unit as a basis for selecting a protocol for signaling with respect to the service control unit. This information is included in the CAMEL subscriber information (CSI) defined in CAMEL phase 1. If required, the CSI (O_CSI; T_CSI) is sent from the home location register to the switching center of the network gateway or to the visitor location register. Consequently, the register records of the home location register do not have to be extended by entries for protocol selection. This also dispenses with a great signaling effort, which arises when there are negotiations on the protocol to be used between the service switching unit and the service control unit. For supporting supplementary services, the service switching units can be retrofitted step-by-step with the corresponding protocols.
The method according to the invention also opens up the possibility of offering new supplementary services quickly and easily if the first and second service switching units belong to different communications networks. Corresponding agreements among the network operators consequently allow new services to be available for a large number of subscribers with little effort. This also makes it possible for individual communications networks to specialize in particular supplementary services.
If the communications network is configured as a mobile radio network, for example a GSM, PCS1900, AMPS, DAMPS or a mobile communications system defined in UMTS, FPLMTS or CTM, a supplementary service for which the subscriber is registered can also be used when the subscriber leaves his own network and is in the range of networks with whose operators corresponding agreements exist. In this case, the service which requires a protocol going beyond CAMEL phase 1 for handling can also be directly supported in visited networks if there are corresponding agreements. If no agreement with the visited operator exists, the service can be used by carrying out a rerouting to a service switching unit in the home network of the subscriber. This wide availability of a supplementary service is important for marketing the service and for rapid acceptance among subscribers.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method of administering supplementary services in a communications network, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.